Staines was asked to attend an interview "in the very near future" in a letter from the ICO sent on Wednesday.

In the letter, which has been seen by MediaGuardian, Staines is asked to reveal the source of his Operation Motorman files.

The blogger said he was considering his response and described the ICO's questions as "comical".

Staines published details of more than 1,000 alleged requests by News International journalists to the private investigator Steve Whittamore for information including ex-directory telephone numbers, criminal record checks and vehicle registration details.

The information was contained in the so-called "blue book" of data retrieved by ICO investigators from Whittamore's home office in 2003. The publication by Staines included names of some of those who were the subject of requests from journalists.

The letter to Staines begins:

"As you are aware the Information Commissioner's Office (ICO) is concerned about the publication of a redacted version of part of the Operation Motorman records which appeared on Guido Fawkes blog site www.order-order.com overnight on the 10 April 2012."

It added:

"The ICO is concerned that your publication of this data has compromised the information rights of individuals. I would therefore invite you to engage with the ICO and submit to an interview to discuss the following topics:
• The source of the database that was published by yourself;
• The extent of your access to the unredacted version of the blue book or whether the copy you obtained was redacted by a third party;
• Your access to copies of the other journals, ie the green, red and yellow books if applicable;
• The security measures you have in place to ensure that the information you hold is kept safe and secure in order to protect against accidental loss or destruction of the information."

The information commissioner, Christopher Graham, earlier this week said the leak was "irresponsible" and a possible breach of the Data Protection Act.

Staines told MediaGuardian: "I'm considering my response – if any. Not sure what jurisdiction the British Information Commissioner imagines he has over an Irish citizen, in Ireland, publishing information on a website hosted in California.

"Some of the questions are comical; reveal your source, tell us what else you have, the measures you have put in place to keep the information safe. I put the information on the internet for everyone to see. In any event this is all covered by publication being in the public interest."

The disclosure by Staines has put the information commissioner under pressure to publish the data behind his office's Operation Motorman investigation, which examined the private trade in information between newspapers, magazines and Whittamore, the private investigator.

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